Lock stitch loop-taker attachment for sewing machines

ABSTRACT

A bracket, and means to attach the bracket to the sewing machine frame below the throat plate adjacent the needle aperture; a shaft journalled in the bracket vertically in parallel with the path of the reciprocating needle; a loop-taker on the top of the shaft; means to transmit rotation to the shaft and the loop taker in synchronism with the reciprocation of the needle; said shaft having an axial aperture throughout its entire length and through the bottom of the loop-taker for the thread from a spool of thread mounted in a convenient position relatively to the sewing machine; the loop-taker has a cup shaped hook body and a guide element in the hook body held stationary for guiding the thread from the cup shaped hook body in the path of the loop formed by the reciprocating needle whereby the said loop locks onto the thread and pulls the thread to the material through said hole forming a lock stitch.

United States Patent 1191 Thompson [451 Apr. 23, 1974 [75] Inventor: George Thompson, Monterey, Calif. [73] Assignee: Archie H. Chevrier, Seaside, Calif.

a part interest [22] Filed: Nov. 24, 1972 [21] Appl. No.: 305,650

52 U.S. c1. .L 112/184, 112/228 [51] Int. Cl D05b 57/14 [58] Field of Search 112/181, 182, 183, 184,

[56] References Cited UNITED STATES PATENTS 1,235,793 8/1917 Gray 112/181 2,098,327 l1/1937 Winkley 112/186 2,095,450 10/1937 Myers 112/184 2,132,892 10/1938 Davidson 112/201 Primary Examiner-Werner H. Schroeder Attorney, Agent, or Firm-George B. White [57] ABSTRACT A bracket, and means to attach the bracket to the sewing machine frame below the throat plate adjacent the needle aperture; a shaft journalled in the bracket vertically in parallel with the path of the reciprocating needle; a loop-taker on the top of the shaft; means to transmit rotation to the shaft and the loop taker in synchronism with the reciprocation of the needle; said shaft having an axial aperture throughout its entire length and through the bottom of the loop-taker for the thread from a spool of thread mounted in a convenient position relatively to the sewing machine; the loop-taker has a cup shaped hook body and a guide element in the hook body held stationary for guiding the thread from the cup shaped hook body in the path of the loop formed by the reciprocating needle whereby the said loop locks onto the thread and pulls the thread to the material through said hole forming a lock stitch.

7 Claims, 13 Drawing Figures PATENTEU APR 2 3 i974 SHEET 2 [IF 3 LOCK STITCH LOOP-TAKER ATTACHMENT FOR SEWING MACHINES BACKGROUND OF THE INVENTION This invention relates to a long existing problem particularly in connection with sewing machines for high speed operation wherein the repeated changing of the bobbin in the bobbin case hinders efficient operation and production.

The primary object of this invention is to provide an attachment to a high speed sewing machine whereby the lower thread beneath the throat plate is provided continuously and without interruption and is positively guided to the loop-taker to form the usual lock stitch operation, and thereby to obviate the need for bobbins or similar devices and the periodic filling and replacing of bobbins.

There were numerous attempts made for the solution of problems caused by bobbins co-operating with looptakers in sewing machines. For instance, the mechanism shown in U.S. Pat. No. 3,407,760 granted to Ketterer which endeavored to provide for the replenishing of thread on the bobbin, which still requires the interruption of operation whereby the machine is either operated for sewing or operated for the purpose of rewinding thread on the bobbin. The object of the herein device is to eliminate the bobbin altogether and eliminate the bobbin rewinding operation and to furnish continuous lower thread supply for the forming of lock stitch by the sewing machine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of the attachment.

FIG. 2 is a perspective view of the attachment in relative position to the throat plate of the sewing machine in the loop-forming position of the needle about to be engaged by the loop taker hook.

FIG. 3 is a fragmental perspective view of the attachment of the throat plate showing the loop taker hook pulling the loop as the loop taker is rotated.

FIG. 4 is a fragmental perspective view showing the loop about to be pulled through the fabric as the loop is cast around the lower thread.

FIGS. 5 and 6 are fragmental views showing the lock stitch forming steps when the fabric is moved in a direction opposite to the movement of the fabric in FIGS. 1 to 4.

FIG. 7 is a fragmental sectional view showing the loop taker engaging the loop at the eye of the needle beneath the throat plate.

FIG. 8 shows the loop taker being pulled as the needle is moved upwardly in the material.

FIG. 9 is a fragmental view showing the loop taker carried further around and being guided over the lower thread as it is also being pulled upward by the needle.

FIG. 10 is a fragmental view showing the loop engaging the lower thread.

FIG. 11 shows the loop interlocked with the lower thread and being pulled toward the material by the needle to form the lock stitch.

FIG. 12 is a diagrammatic view of a sewing machine showing the drive connection and the attachments.

FIG. 13 is a cross-sectional view of the attachment together with a diagrammatic view for guiding the thread from a spool into and through the shaft and the loop taker.

DETAILED DESCRIPTION As shown in FIG. 12 the sewing machine frame 1 is provided with a throat plate 2 which has an aperture 3 to accommodate the usual needle 4 which is reciprocated by the needle stem 6 by the usual drive mechanism of a sewing machine. The needle thread 7 is guided from a usual spool 8 through rollers 9 in the usual manner to the eye in the point 11 of the needle 4. The loop taker attachment I2 is driven by a suitable gear transmission 13 from a drive shaft 14 journalled in bearings 16 underneath the sewing machine. The drive shaft 14 has a driven pulley 17 on its end connected by a belt 18 to a drive pulley 19 to be driven in synchronism with the reciprocation of the needle. A spool of thread 21 is suitably supported so that the lower thread 22 can be guided around rollers 23 to the loop taker attachment 12.

The loop taker attachment is mounted by a loop taker bracket 26 on the frame of the sewing machine. The loop taker bracket as particularly shown in FIG. 1 has a mounting foot 27 with an elongated slot 28 to accommodate the usual mounting bolts, not shown, with some flexibility of adjustment for locating the bracket in the correct position relatively to the needle 4. The bracket 26 has an upper bearing 29 and a lower bearing 31 perpendicularly spaced from one another on an axis parallel with the path of reciprocation of the needle 4. On one side of the bracket 26 is a split bearing 32 of the usual type for accommodating the drive shaft 14. The gear transmission 13 is on the end of the drive shaft 14 adjacent the split bearing 32. A spiral gear 33 is located between the bearings 29 and 31 in registry with the gear transmission 13 adjacent the split bearing 32.

A hook shaft 34 is journalled in suitable journals in bearings 29 and 31 and extends and is suitably keyed to the driven spiral gear 33. The hook shaft has an axial passage 36 therethrough. The actual journalling of the hook shaft 34 in the lower bearing is through the hub 37 of the driven spiral gear 33 which hub is journalled in the lower bearing 31. An eccentric cam 38 is on the top of the hook shaft 34 for a purpose to be hereinafter described. The shoulder 39 formed by the eccentric cam 38 serves the purpose of resting on the top of a bearing top 41 in an enlarged recess 42 in the top of the bracket 26. Thus the hook shaft 34is inserted, in assembling from the top. A reduced tip 43 extends from the lower end of the hook shaft 34 as shown in FIG. 13 for the purpose of facilitating the threading of the thread through the passage 36 of the hook shaft 34.

A loop taker 44 is fixed on the top of the shaft 34 and to the top of the eccentric cam 38 so as to rotate with the shaft 34. The loop taker 44 has a cup-shaped hook body 46 the bottom 47 of which has a hole 48 therethrough in registry with the passage 36 of the shaft 34 so that the lower thread passes through the hole 48. The cup-shaped body has a cut away portion on its periphery on one side of which is formed a thread guiding edge 49. The flange or side on the other side of the cut ofi portion is formed into a hook or loop seizing beak 51 which projects over a cut away portion 49.

In the cavity of the cup-shaped body 46 is a spacer rib 52. A thread guide 53 has a spacer rib flange 54 which rests on the spacer rib 52 so that there is a space below the bottom 56 of the guide 53 and above the hole 48. Thus the thread emerging from the hole 48 extends along the guide bottom 56 and through an opening 55 to and over the top of the guide 53. The thread guide 53 is in a generally cylindrical shape and is held in the cup-shaped body 46 by a gib 57 which latter in turn is held by screws 58 on the top of the body 46 opposite the beak 51. The gib 57 overlaps inwardly the top of the cylindrical guide 53. The guide 53 is prevented from rotating with the cup-shaped hook body 46 by a pair of spaced ribs 60 on the bottom face of the throat plate 2, straddling an ear 61. Aligned cut away portions of rib 52 and flange 53 afford upward passage to the lower thread 22.

Initially the lower thread 22 is held taut by pulling its free end through a hole 62 of a finger 63. This finger 63 is supported on a vertical arm 64 by a suitable screw 66. The vertical arm extends from the end of a horizontal arm 67. A hub 68 of the horizontal arm is pivoted in the bracket recess 42 by means of a pivot pin 69 which extends into a pivot hole 71 in the bottom of the recess 42 offset to one side of the shaft 34. A link 72 has a hole 73 in one end thereof fitting over the eccentric cam 38 and has a hole 74 in its other end fitting over a pivot stud 76 on the horizontal arm 67 so that as the hook shaft 34 is rotated the eccentric cam 38 oscillates the link 72 and thereby oscillates the finger 63.

In operation the lower thread from the spool 21 is threaded through the tip 43 and through the passage 36 of the hook shaft 34 and out through the hole 48 and the opening 55 up over the top of the guide 53 and into the hole 62 of the finger 63 thus to be held under some tension. Then the high speed sewing machine is ready for operation continuously because when all the thread from the spool 21 is unwound, then the end of the thread on the next replacement spool 21 is tiedto the end of the thread from the preceding spool and is pulled through. In this manner the sewing machine can be in continuous operation without interruption for changing or rewinding bobbins. The initial position of the end of the lower thread is shown in FIG. 2 and the lower thread 22 is shown in heavier line. As the needle 4 descends through the fabric 77 and through the needle aperture 3 of the throat plate 2 it forms a loop 78 below the throat plate 2. The rotating loop taker body 46 rotates in a clockwise direction viewing FIG. 2 so that the hooking beak 51 moves toward the loop 78 and pulls the loop around into and toward the position shown in FIG. 3. The steps in FIG. 3 and FIG. 4 illustrate the position ofthe lower thread 22 after the initial lock stitch has been produced and thereby the end of the lower thread 22 is pulled out of the hole 62 of the finger 63 and is held in tension and is being pulled by the fabric 77 on the sewing machine. Thus as shown in FIG. 3 the hooking beak 51 pulls the loop 78 around so that the loop straddles the lower thread 22 as shown in FIG. 4 and as the needle 4 further rises it pulls the loop 78 tightly around the lower thread 22 and interlocks with it as the needle thread 7 pulls through the fabric 77 as shown in FIG. 11. The sequence of operation is also illustrated in FIGS. 7 to 11 inclusive, wherein in FIG. 7 the loop 78 is formed and is hooked by the beak as shown in FIG. 8 and is pulled around as shown in FIG. 9 so that it straddles the lower thread as shown in FIG. 10 as it is pulled upward by the needle 4 for tightly interlocking as shown in FIG. 11. FIGS. 5

and 6 illustrate the above operation when the fabric is moved in a direction opposite to the direction in FIGS. 1 to 4. The ribs and the bottom face of the throat plate 2 are spaced from the car 61 so that the upper part of the loop extending over the top of the guide 53 is pulled through the space around the ear 61 and thus is kept above the lower thread 22. While reference is made here to spools, it is to be understood that on commercial sewing machines the thread is furnished on socalled cones in larger quantities.

I claim:

1. In a loop-taker device for a sewing machine having a reciprocating needle with needle thread fed into the. eye in the point of a needle, said needle being reciprocated through a needle aperture through a throat plate,

a loop-taker supporting bracket adapted to be secured to said machine adjacent and below said needle aperture,

a hook shaft journalled in said bracket,

a loop-taker body on the end of said shaft adjacent said throat plate,

a substantially annular hook flange on said body formed into a loop catcher beak substantially tangential to the direction of rotation of said body for catching the loop formed by the needle thread below said throat plate, thereby to pull said loop around,

means held fixedly relatively to said loop-taker body and in operative relation to said catcher beak to hold a lower thread in the path of said loop for interlocking engagement thereby to form a lock stitch as said needle is being pulled outwardly of said needle aperture,

guide means through the hook shaft to guide the lower thread directly through the hook shaft to said loop-taker body from a spool spaced from the looptaker body to enable said loop-taker device to pull thread from the spool whenever said sewing machine is operatively performing stitching,

and means to rotate said hook shaft and said looptaker body in synchronism with the reciprocation of said needle. 2. The loop-taker device specified in claim 1, and

said lower thread guide means including a passage leading through the bottom of said loop-taker body to said fixedly held means.

3. The loop-taker device specified in claim 1, and

said lower thread guide means being a passage through said hook shaft opening at one end into the bottom of said loop-taker body.

4. The loop-taker device specified in claim- 3, and

said fixedly held means being an element nested in said loop-taker body having a passage therethrough to guide said lower thread toward the periphery of said flange thereby to hold said lower thread in the path of said loop.

5. The loop-taker device specified in claim 1, and

the journal axis of said hook shaft being substantially parallel with the path of reciprocation of said needle, and

said lower thread guide means including an axial passage through said hook shaft, an end of said passage opening into the bottom of said loop-taker body for guiding said lower thread to said fixedly held means.

6. The loop-taker device specified in claim 5, and

locked therewith during the movement of said needle out of said needle aperture and thereby to form a lock stitch on the fabric sewn on said throat plate.

7. The loop-taker device specified in claim 6, and means on the throat plate to hold said insert fixedly against rotation relatively to said loop-taker body. 

1. In a loop-taker device for a sewing machine having a reciprocating needle wIth needle thread fed into the eye in the point of a needle, said needle being reciprocated through a needle aperture through a throat plate, a loop-taker supporting bracket adapted to be secured to said machine adjacent and below said needle aperture, a hook shaft journalled in said bracket, a loop-taker body on the end of said shaft adjacent said throat plate, a substantially annular hook flange on said body formed into a loop catcher beak substantially tangential to the direction of rotation of said body for catching the loop formed by the needle thread below said throat plate, thereby to pull said loop around, means held fixedly relatively to said loop-taker body and in operative relation to said catcher beak to hold a lower thread in the path of said loop for interlocking engagement thereby to form a lock stitch as said needle is being pulled outwardly of said needle aperture, guide means through the hook shaft to guide the lower thread directly through the hook shaft to said loop-taker body from a spool spaced from the loop-taker body to enable said loop-taker device to pull thread from the spool whenever said sewing machine is operatively performing stitching, and means to rotate said hook shaft and said loop-taker body in synchronism with the reciprocation of said needle.
 2. The loop-taker device specified in claim 1, and said lower thread guide means including a passage leading through the bottom of said loop-taker body to said fixedly held means.
 3. The loop-taker device specified in claim 1, and said lower thread guide means being a passage through said hook shaft opening at one end into the bottom of said loop-taker body.
 4. The loop-taker device specified in claim 3, and said fixedly held means being an element nested in said loop-taker body having a passage therethrough to guide said lower thread toward the periphery of said flange thereby to hold said lower thread in the path of said loop.
 5. The loop-taker device specified in claim 1, and the journal axis of said hook shaft being substantially parallel with the path of reciprocation of said needle, and said lower thread guide means including an axial passage through said hook shaft, an end of said passage opening into the bottom of said loop-taker body for guiding said lower thread to said fixedly held means.
 6. The loop-taker device specified in claim 5, and said fixedly held means including, a generally cylindrical insert resting inside said flange of said loop-taker body spaced from the end of said hook shaft passage in said body, a guide wall and an aperture in said insert to guide said lower thread from the bottom of said loop-taker body into the path of the loop of the needle thread so as to be straddled by said loop and interlocked therewith during the movement of said needle out of said needle aperture and thereby to form a lock stitch on the fabric sewn on said throat plate.
 7. The loop-taker device specified in claim 6, and means on the throat plate to hold said insert fixedly against rotation relatively to said loop-taker body. 